High-intensity interval training isn't just for keeners

Jill Barker, Montreal Gazette09.28.2016

This image released by NBC shows contestant Rachel Frederickson during the first episode of "The Biggest Loser." Fredrickson lost nearly 60 percent of her body weight to win the latest season of "The Biggest Loser" and pocket $250,000. A day after her grand unveiling on NBC, she faced a firestorm of criticism in social media from people who said she went too far.

When someone mentions high-intensity interval training, you probably picture young, fit gym rats pushing themselves to the limit. But new evidence suggests that short, intense bouts of exercise could be the next big thing for those more comfortable in plus-size clothing than a tank top and short shorts.

Lauded primarily for its ability to achieve the same fitness benefits as moderate intensity workouts but in less time, high-intensity interval training — or HIIT — has become a popular choice among time-crunched fitness fanatics. But up until recently, it has been generally considered too harsh a workout for anyone new to exercise and those who carry extra weight.

Little is known, though, about the role HIIT plays in getting rid of excess inches, which is generally considered best achieved through longer, steady workouts. And studies that have used HIIT to take off pounds have demonstrated mixed results. So in an attempt to find out more about the effect of HIIT on weight loss and cardiovascular and metabolic fitness, a research team out of Norway divided 46 moderately obese men and women into three groups and had them follow a 12-week exercise routine on a stationary bike.

First, the researchers took measurements for weight, height, waist and hip circumference and tested cardiovascular fitness (V02 max), resting metabolic rate (the number of calories burned at rest), food intake and insulin levels. Then the groups got started.

The HIIT exercisers sprinted as hard as they could (the equivalent of 85-90 per cent of their maximal heart rate) for eight seconds followed by 12 seconds of turning the pedals as slowly as possible with the total duration of the workout individually prescribed to burn 250 calories – about 20 minutes.

The second group performed a half-HIIT workout, which followed the same protocol as the HIIT but for only about 10 minutes, burning about 125 calories.

The third group cycled at a lower intensity (70 per cent of maximal heart rate) and continuous pace for about 32 minutes to burn 250 calories.

The results? All three training programs similarly improved body weight and composition, resting metabolic rate, insulin sensitivity and cardiovascular fitness, which was a surprise to the research team. They expected the HIIT and the lower-intensity continuous exercise workout to post similar results, but didn’t anticipate the 10-minute, half-HIIT workout would be as effective as the other two at improving fitness and body composition.

It demonstrates “that in sedentary obese individuals, even a very small volume of exercise can induce improvements in metabolic and cardiovascular factors,” the authors said.

Admittedly, the changes in body weight and composition and cardiovascular fitness by everyone involved weren’t huge, but the fact that similar results can be realized in 10 minutes versus 32 minutes is the real eye-opener.

“The present study adds new important data to the current controversy regarding the efficacy of HIIT versus moderate-intensity continuous training, on body weight and composition and metabolism in general,” the Norwegian research team said.

What does this mean for the average exerciser trying to get in better shape and lose a few pounds? Well, it offers insight into the benefits of short-duration, high-intensity workouts, and confirms that even 10 minutes of exercise has the potential to make a difference. That said, those 10 minutes need to include bouts of exercise that border on the uncomfortable, something the unfit generally try to avoid. But that’s the trade- off if lack of time is one of the reasons you don’t hit the gym more often.

How uncomfortable are we talking? The intensity of the exercisers in this study was in the range of 80-95 per cent of their maximal heart rate, which is the equivalent of pushing yourself to the limit. The upside is that the extreme effort was short-lived – just eight seconds. In practical terms, that means walking, swimming, running or cycling as fast as you can and as hard as you can and staying there for the full eight seconds.

If, like the individuals in this study, you’re new to exercise and carry excess weight, performing your HIIT workouts on a bike is a smart decision. Cycling is a non-impact workout that is gentler on your joints than running or walking, which makes it easier to add that extra effort. Also worth keeping in mind is that not all HIIT workouts are the same. The results of eight seconds of effort and 12 seconds of taking it easy might not be the same when the intervals are slightly longer.

But that doesn’t mean HIIT intervals aren’t for you.

Devoting 10 minutes a day to exercise is decidedly easier to fit into a busy lifestyle than 30-minute workouts, which is the plus side of pushing your physical limits. And who’s to say that your exercise routine should be limited to high-intensity, short-duration interval workouts.

Mixing it up between a long walk on nights when you need to chill out and early-morning speed workouts done before the kids get up is a workable plan. Best of all, in a few weeks you’ll be fitter and leaner all by making “short and tough” your new mantra.

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High-intensity interval training isn't just for keeners

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